Process of making acid calcium phosphates.



' ing acid calcium phosphate rom phosphate 20. cal in the treatment of low-grade phosphate I UNITE STATES PATENT OFFICE.

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To all whom it may concern:

Be it known that I, HENRY BL MnN- mane, Jr., a citizen of the United States,

residing at Los Angeles, in the county of Processes of Making Acid Calcium Phos-v phates, of which the following is a specification.

My invention relates to a rocess of makrock.

Theusual process of converting phosphate rock into acid calcium phosphate, the socalled superphosphate of commerce, widely used as a fertilizer, uses sulfuric acid in the reduction process.

The disadvantage of this process is that sulfuric acid isdestructive to the apparatus employed and, furthermore, is not economirock, for the reason that said acid will act on the impurities carried by the phosphate, such as iron ,oxids, calcium fluorid and aluminum silicates. The present process proposes to convert phosphate rock to acid calcium phosphate, using ammonia and carbon-dioxid as rea ents, which ,may be regenerated and use in the succeeding cycles of operation. Again, if through any carelessness, or other cause, ammonia should be left inthe acid'ealcium phosphate, it would not injure the product, but, on the contrary, would improve the same, since ammonium salts are valuablefertilizers,-and would ,be

paid'for on analysis of the product. 1

My invention consists of the steps in the new rocess hereinafter described and claimed.

Phosphate .rockis ground finely to an impalpable powder an passed through 200 mesh screen and mixed with water to form a phos hatic magma or pulp. I preferably roast t e phosphate rock from three to five hours before inding, which not only facilitates the grinding process, but also the chemical reactions of the recess. The phosphatic magma is next sub e'cted to treatment 'with carbon dioxid and ammonia ases,

j carbonate and nor am- Patented Jan. 1, 1918.

monium phosphate in accordance with the following I have found that the temperature most favorable for the reaction is from to 70 F. and that a pressureof 150 lbs. greatl facilitates the rapidity of thereaction. 1%

will be understood that I do not limit myself to the temperatures or to the pressures stated.

When the reaction is complete, the mixture is filter-pressed, the calcium carbonate and other insoluble material of the phosphate rock stayin in the filter-press and the ammonium phosp ate staying in the filtrate. This reaction is based on the dissolving action of carbon dioxid gas on calcium phosphate,; which, in the presence of ammonia, precipitates the calcium in the calcium phosphate as calcium carbonate, and the phosphoric acid "radical combines-with the ammonia, forming ammonium phosphate, which is readily formed -when the liquors are kept alkaline by an excess of ammonia. As can be readily seen, the reaction can be kept under absolutecontrol by the amount of am monia and carbon dioxidgases led into the phosphatic magma or pulp. Furthermore, any of the ammonium ortho-. hosphates can that are led or forced through the phosp atic magma.

Afterthe reaction, as above described,

finished, there are three different ways of making mono-calcium phosphate:

1. ixing the ammonium phosphate produced by the above process with a fresh;

- be produced, depending so ely upon the amount of ammonia and carbon dioxid ases produced by the above process to the crystallization point and, mixing the crystals with finely ground crude. phosphate rock, and heating the same until all the ammonia is driven off as a gas, which is collected in the gasometer, the phosphoric radical com- 3 bining with the phosphate rock to produce terial, consisting in treatin mono-calcium phosphate.

3. Heatin formed by t e above described process until the ammonia is driven off and collected in a gasometer, and mixing the remaining phosphoric acid with a finely ground crude phosphate rock to produce mono-calcium phosphate.

The reactions taking place in the three modifications of the process just described are as follows:

Various changes in the steps of the process may be made by those skilled in the art without'departing from the spirit of my in-- vention as claimed. For instance,in place of ammonia and carbon dioxid, I may use. ammonium carbonate, either the normal or the acid ammonium carbonate, and carry out the succeeding steps of the process as described. r I claim:

1. A process of treating phosphate mapowdered calcareous phosphate materia with ammonia and carbon dioxid in thepresence of water,

thereby forming calcium carbonate and amphosphate rock to the action of ammonia the ammonium phosphate I and carbon dioxid in the presence of water, thereby formm calcium carbonate and ammonium hosp ate, separating the ammon um p osphate from the mixture, and heating t e same to drive off the ammonia -monium phosphate, separating the ammonium phosp ate from the mixture, heating the same to drive off the ammonia and,

produce phosphoric acid, and treating powdered (phosphate rock with said phosphoric aci to produce acid calcium phosp ate.

5. A process of treating phosphate material, consisting of subjecting phosphate rock to the action of ammonium carbonate in the presence of water, thereby forming calcium carbonate and ammonium phosphate, and separating the ammonium phosphate from the mixture.

6. A process of treating phosphate material, consisting of subjecting phosphate rock to the action of ammonium carbonate in the presence of water, thereby forming calcium carbonate and ammonium phosphate, separating the ammonium phosphate from the mixture, and heating the same to drive .ofi' the ammonia and produce phosphoric acid.

7 A process of treating phosphate ma terial, consisting of subjectmg phosphate rock to" the action of ammo-mum carbonate in the presence of water, thereby forming calcium carbonate and ammonium phoshate, separating the ammonium phosphate rom the mixture, heating the same to drive off the ammonia and-produce phosphoric acid, and mixing powdered phosphate material withvsaid acid.- in proportion to pro duce acid calcium phosphate.

In testimony whereof- I have signed my name to this specification.

.HENRY BLUMENBERG, J1; I 

